SAN FRANCISCO Using a genetically modified version of the smallpox virus, a team of US researchers has managed to prolong the life of some patients with end-stage liver cancer, in many cases managing to reduce the size of the tumor by more than 50%. This result – which paves the way for the development of "viral" treatments for cancer – was achieved by David Kirn and his colleagues at Jennerex Biotherapeutics (San Francisco). The idea that some viruses can somehow eliminate or contain tumors dates back to the early 1900s; it was in fact precisely in 1912 that an Italian scientific journal of gynecology published an article relating to the case of a woman suffering from cervical cancer who had undergone a reduction of the neoplasm after receiving the vaccine against wild rabies. But now Kirn and co-workers are very close to solving the problem. They started working on the vaccinia virus - that is, the microorganism responsible for smallpox - to which they attached a molecule (actin) like a "tail" which allows it to spread very rapidly within human cells. Scholars also modified this virus so that it was no longer capable of synthesizing an enzyme known as thymidine kinase; without it, the vaccinia virus is no longer able to reproduce and therefore to damage healthy cells. But since cancer cells produce the enzyme in question in large quantities, the aforementioned microorganism can reproduce exclusively in them; not only that, once it has multiplied a sufficient number of times, the vaccine virus causes the death of the cancer cells it uses. And it's not over. Kirn added a gene to his GM viruses that allows them to produce a type of cytokine, a molecule that acts as a booster for the human body's immune cells (which end up attacking tumor tissue). After successfully testing the virus on rabbits, the scientists selected 13 volunteers suffering from end-stage liver cancer and injected them several times with the GM microorganism: in 10 cases the tumors shrank (in five cases the reduction exceeded 50% of the total) and the life expectancy of patients has considerably lengthened. Free of 28/10/2007, article by ROBERTO MANZOCCO p. 31
